Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
High speed public transportation is being deployed worldwide at an increased pace. Hence, providing multiple services of good quality to users on high speed vehicles is important yet more challenging than typical mobile wireless environments also due to the following reasons:                Reduced Handover Success Rate: for high speed UEs, handover occurs much more frequently. With a mass of UEs performing handover at the same time, the handover success rate is reduced, due to excessive signaling overhead and the fact that tracking area update (TAU) is provided in a short time period. Furthermore, UE measurements in high speed environments are typically less accurate than low speed environments.        Degraded Throughput due to High Doppler Effects: impairments caused by high Doppler include frequency estimation errors and channel estimation errors. The achievable throughput with these impairments can be significantly reduced compared to low speed environment. Specific eNB/UE implementations to combat these impairments are possible, at the expense of additional cost.        
To overcome the issues of reduced handover success rate and/or degraded throughput due to high Doppler effects, installing a communication apparatus on the train, and relaying the wireless communication between end user and on-land base station is one good candidate solution, wherein the relay communication apparatus can be either one Relay Node defined in 3GPP or one Wireless Router.
Mobile Relay is proposed in Reference [1] (RP-110894, 3GPP TSG RAN#52, May 31-Jun. 3, 2011). Mobile Relay is enhanced based on the Relay Node defined in Reference [2] (3GPP TS 36.806 V9.0.0, March, 2010).
According to definition for mobile relay in Reference [1], one of mobile relay's major characters is the capacity to support group mobility. The reason to support group mobility is that excessive handover signaling can be avoided by performing a group mobility procedure instead of individual mobility procedures for every UE, so handover success rate can be improved via mobile relays capable of group mobility.
Three major problems of the current RAN technology (including Relay Node defined in Reference [2]) in high speed public transportation scenario are listed as the following. With the Mobile Relay, the following problems can be overcome.                With a mass of UEs performing handover at the same time, the handover success rate is reduced, due to excessive signaling overhead in a short time period.        UE measurements in high speed environments are typically less accurate than low speed environments.        When the Relay Node moves to edge of two adjacent donor cells, the throughput of Relay Node in Un port will be very limited for the big path loss and high inter-cell interference.        
Wireless Router is another kind of communication apparatus that can be used to relay wireless communication between end user and on-land base stations. The Wireless Router communicates with end user via WIFI, and communicates with the on-land base station via 3G (CDMA2000/TD-SCDMA/WCDMA) or LTE.
The current Wireless Router can only support one radio link between on-land base station and itself. So when one Wireless Router moves across the edge of two neighbor cells, the quality of the radio link will be very poor, and herein the supported throughput will be limited.